This invention relates to injection molding tire treads, especially ring treads and continuous treads which are molded in a generally cylindrical segmental mold having a core and radially movable segments forming a mold cavity. A container ring is movable into engagement with the segments during closing of the mold to retain the segments in position during injection and curing. By modifying the apparatus of this invention, it may be used to injection mold ring treads of continuous treads extending from the mold cavity through the side of the container ring from a space between two of the segments. The continuous tread may be cut to a desired length at the time of use for adherence to a new tire casing or to a tire to be retreaded by a suitable adhesive.
Heretofore, it has been proposed to make ring treads by injection molding the tread in a mold cavity between a core and continuous mold halves. It has also been proposed to make a continuous tread by feeding a strip of unvulcanized rubber onto a rotating cylinder and then enclosing the strip with mold segments rotating with the cylinder and radially movable into engagement with the cylinder. The tread is cured by container molding and is then removed from the cylinder as the mold segments are moved radially away from the cylinder. Continuous tire treads have also been made by passing an extruded rubber strip between cooperating mold segments carried by respective endless belts which apply suitable temperatures and pressures to the strip to produce the surface designs. The molded uncured rubber strip is then removed from the molds and cured by applying radiation or heat.